Rod, with regard to knife-edging the counterweights, you need to be sure that
you
still have proper weight to offset the piston/rod weight. Knife-edging was
primarily used to lessen the effects of the crank passing through oil in the
sump
as it rotated. John
RodsINTOMG@aol.com wrote:
> Hello all,
>
> I am contemplating building a ground up race engine for my MGB vintage racer
> and have a question on crankshafts. While there may not be that many on the
> list that are running MGBs, there are some that run Elvas and I'm sure that
> someone can point me in the right direction.
>
> My question has to do with the book, How To Power Tune MGB 4 Cylinder Engines
> by Peter Burgess. On page 43 the author states that there two types of
> factory (five main) crankshafts used in the MGBs: the early B's crankshaft was
> replaced by a cast iron one. Surprisingly, the cast crank is the superior of
> the two being better balanced with better wear characteristics. The best cast
> crank is the flat-sided one to be found in the 18v engines from 1971 to
> '74...The early crank in not flat but has offset counter weights.
>
> My limited experience with Chevys says that a (forged?) steel crank is
> superior to a cast iron crank. A fellow MGB racer says that the crank with
> the offset weights (the steel crank) is the one to use. I'm now confused. At
> this stage of the project, I have access to either crankshaft. Is Peter
> Burgess right about the later flat-sided, cast iron crank being the one of
> choice?
>
> My crankshaft grinder says he can turn down the crankshaft (he was looking at
> my 3 main crank, which is the flat type, when he told me this) in a lathe and
> cut the counter weights to a near knife edge thus taking a lot of weight out
> of the crank for improved performance; Any thoughts on this?
>
> Rod Schweiger
> '64 MGB Sebring Replica
|